We believe that mirror matter exists but cannot comprise all DM. Thus, the cases where \(\alpha = 0\)  (there are no mirror baryons) and \(\alpha = \Omega _{\rm DM}/\Omega _b=5.33\)  (all DM is made of mirror baryons) should be excluded. Although we can expect that the mirror baryonic density is approximately equal to the ordinary one [1]}, [2]}, [3]}, small \(b^{\prime }b\)  ratio \(\alpha \lesssim 0.3 - 0.8\)  is also suggested [4]}. A conservative upper and lower bounds of the \(b^{\prime }b\)  ratio
\(0.1 \le \alpha \le 5,\) 
